Hot water running hot then cold then hot...

[OLTB]

Evening all.

As above really - new combi-boiler fitted last year (Worcester) and when I run the hot tap, it takes an age for the water to heat and then it starts to run cold and then hot again. Any help appreciated and I’ll contact the heating engineers who installed it.

Many thanks, OLTB.

[tacpot12]

Has it always done this or is this new?

[AsleepInYorkshire]

Blockage in the hot water heat exchanger?

AiY

[Mike4]

This is usually contamination of the domestic hot water heat exchanger.

It can be either water scale on the domestic water side or corrosion deposits on the primary water side. Did the installers of your new boiler carry out a thorough power flush of your heating system before fitting the new boiler? (This takes several hours or a short day, done properly.)

[OLTB]

Thanks all - just started doing it the last few days and I think I remember them saying they were doing a full flush through - the dismantling of the old system and new location and installation of the new system took about 3 days last year. We live in a hard water area and they fitted some sort of filter to the pipes just under the boiler that I think helped with the hard water. Thanks for the advice about the heat exchanger and I’ll mention this when I book the appointment so they can bring a spare one if needed.

Cheers, OLTB.

[bungeejumper]

The filter ting below the boiler will have been a dirt trap (Worcester Bosch's equivalent of a Magnaclean), which catches iron deposits in the circulating water, so that they can be cleaned out once a year during the annual service. It doesn't have any contact with the actual domestic hot water flow, though.

You've got a ten year warranty with your boiler, so maybe you should just ask the installers?

BJ

[Mike4]

The filter ting below the boiler will have been a dirt trap (Worcester Bosch's equivalent of a Magnaclean), which catches iron deposits in the circulating water, so that they can be cleaned out once a year during the annual service. It doesn't have any contact with the actual domestic hot water flow, though.

You've got a ten year warranty with your boiler, so maybe you should just ask the installers?

BJ

Or better, ask the company (Worcester), giving the guarantee!